"This mode of grafting the walnut, besides requiring a hothouse, needs the care of a skillful person to make it succeed. So are grafted the little trees that we import from France, and that we plant in nursery rows and offer to the public." For other modes of root grafting, I refer the reader to those recommended for the hickories, in the preceding chapter. Propagating walnuts by layers is practicable, where the small trees have been cut down to force out new shoots near the surface of the ground, then bent down and covered with soil in the usual method of layering woody plants. =Planting and Pruning.=--The plants will produce a greater number of fibrous roots if the nuts are planted in light, loose, but rich soil, than in a heavy, tenacious one; but with all kinds it is best to transplant when one or two years old, and cut off a portion of the taproots, as recommended for the hickories. When removed from the nursery rows for final planting, prune away nearly or quite all side branches, leaving only the terminal bud if the trees are not more than six to eight feet high. After final planting where the trees are to remain permanently, very little pruning will ever be required, further than to cut away branches that may cross each other, or to shorten some to give proper form to the head. No tree in cultivation requires less pruning than walnuts. As a genus of trees the walnuts flourish best in deep, rich loam, rather light than heavy, and in this country require considerable moisture at the roots, and some, like the butternut, succeed best in bottomlands, near creeks and larger streams. If the soil is naturally too dry for such trees, the fault can be readily remedied by the use of some form of mulch applied to the surface of the soil around the stem after planting, renewing this annually, or oftener if necessary, until the trees are large enough to shade the ground. Walnut trees, as well as the closely allied hickories, are well adapted for roadside planting, and when set in such positions are far less likely to be injured by insects than when planted in orchards or large groups, besides serving a double purpose, being ornamental as well as useful. They may also be planted around buildings, and where other and less valuable trees are generally grown. There are also millions of acres of rocky hill-sides and old fields which might be utilized for nut orchards, and if rather widely scattered over such land they would prove beneficial in shading the pasture grasses. First of all, however, let us have rows of these trees along all our country roads, after which it will be time enough to begin planting them elsewhere. SPECIES AND VARIETIES OF WALNUTS.